1. Field of the Invention
This invention relates to an improved image receiving medium for use in combination with a thermal image transfer recording medium in a sublimation-type thermal image transfer recording system.
2. Discussion of Background
A sublimation-type thermal image transfer recording system is characterized by employing a thermal image transfer recording medium which comprises a dye transfer layer containing a heat-sublimable dye, and an image receiving medium capable of receiving the dye which is sublimed when the thermal image transfer recording medium is superimposed on the image receiving medium and heated from the back side thereof. Since the above recording system can produce a full-colored hard copy with an excellent half tone, comparable to a color photograph, it is greatly attracting public attention now.
A thermoplastic resin which can be readily dyed with a heat-sublimable dye, such as a polyester resin, has been used for a dye receiving layer of the conventional image receiving medium for use in the sublimation-type thermal image transfer recording system. The thermoplastic resin, however, has a low thermal resistance, so that the image receiving medium readily fuses when thermal recording is conducted, and sticks to a thermal image transfer recording medium (color sheet). As a result, the image receiving medium cannot be easily released from the thermal image transfer recording medium after the recording.
In order to solve the above problem, a releasant such as a silicone oil has been incorporated into a dye receiving layer of the image receiving medium.
In the case where a silicone oil is incorporated into the dye receiving layer, the image transfer recording medium can easily be released from the image receiving medium after thermal recording. The degree of ease of the release becomes high as the amount of the silicone oil incorporated increases. The use of a large amount of silicone oil, however, decreases the adhesion between a substrate and the dye receiving layer formed thereon. As a result, the dye receiving layer is peeled off the substrate and is transferred to the image transfer recording medium after thermal recording. In addition, the use of a large amount of silicone oil makes the surface of the dye receiving layer excessively slippery, so that the image receiving medium cannot normally move on the image transfer recording medium.